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RURAL INDUSTRY RESEARCH FUNDS FINAL REPORT
COTTON RESEARCH COUNCIL DAN 14L
EVALUATION OF THE INSECTICIDE MANAGEMENT STRATEGY FOR RESISTANT HELIOTHIS ARMIGERA - NAMOI/GWYDIR
Entomology Field code: 3.1 Department of Agriculture, NSW
P O Box K220 Haymarket 2000
Dr E C Wolfe, Regional Director of Research Tel: 067-679300 Dr V Edge, Director of Entomology
Tel: 02 -6300251 Research staff: Mr N W Forrester, Special Entomologist
Agricultural Research Station
PMB Myall Vale
Narrabri 2390 Tel: 067-931105 Administrative contact: Mr G M Mohr, Research Co-ordinator
Tel: 02 -2175130 Commencement and completion dates: July 1984, June 1987
OBJECTIVES
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To evaluate the impact of the Insecticide Resistance Management Strategy on pyrethroid and endosulfan resistance levels in Heliothis armigera in the Namoi/Gwydir.*
To determine the main factors influencing resistance frequency. BUDGET SUMMARY1984/85 1985/86 1986/87 36,000 49,000 51,000 RESULTS
A new monitoring technique has been devised which enables individual larvae to be screened for pyrethroid/endosulfan resistance directly from the field without changing their genetic makeup. The technique involves screening larvae, collected as eggs in the field, with a discriminating dose of either fenvalerate or endosulfan. This new technique has proved quite sensitive in detecting even small differences in resistance levels. It has also avoided the long delay and altered genetic makeup associated with the classical Fi bioassay method.
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'· "Page 2A. PYRETHROIDS
The pyrethroid. resistance levels detected over the past four seasons in the Namoi/Gwydir and the past two seasons at Emerald are:-
% Pyrethroid Resistance
Stage 1 Stage 2 Stage 3 Namoi/Gwydir
1983/84 9.4 8.5 14.9
1984/85 7.2 13.1 28.2
1985/86 7.6 13.5 45.2
1986/87 33.0 36.7 42.7
Emerald
1985/86 6.5 17.4 16.5
1986/87 8.8 27.2 32.0
The main points to emerge from this work are:-
i) Stable Stage 1 resistance level (except for 1986/87) ii) Increase in resistance from Stage 1 to Stage 2,
particularly at Emerald. This has been shown to be due to selection of adults prior to egg laying. This selection is most important when it occurs prior to mating at Emerald, where maize is a major alternative crop to cotton in the Irrigation Area.
iii) Increase in resistance from Stage 2 to Stage 3 due to larval selection in Stage 2. The level of resistance in this Stage is determined by the interaction of two
main factors: pyrethroid selection pressure in the previous generation and the degree of dilution from immigrating susceptibles. For example, high pyrethroid use and a summer drought in 1985/86 resulted in high pyrethroid resistance in the Namoi/Gwydir; while lower pyrethroid use and a wet summer resulted in much lower levels in 1983/84.
iv) High Stage 1 resistance in 1986/87 due to high survival of the highly resistant overwintering pupae. This was caused by a lack of cultivation of cotton residues precipitated by record low cotton prices.
Other work has shown the potential problems with using pheromone trapped male moths to determine resistance levels, without accounting for moth age.
Another significant finding has been the documentation that low rates of pyrethroids used against sorghum midge, can select for pyrethroid resistance in any Heliothis armigera present at spraying.
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B. ENDOSULFAN
The endosulfan resistance levels detected in the past season were:-
NamoiGwydir 1986/87 Emerald
1986/87
% Endosulfan Resistance Stage 1 Stage 2 Stage 3
6.4 17.0 20.6
7.6 20.S 17.6
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These results indicate a small response to selection pressure, which has been also demonstrated in laboratory selection experiments. However, as long as endosulfan useage patterns do not change dramatically, this level of resistance is probably quite manageable.
BENEFITS TO THE INDUSTRY
i) The industry has regular access to the latest pyrethroid and endosulfan resistance levels. Without this information, industry compliance with the strategy may well have quickly diminished, with disastrous consequences for the whole industry.
ii) The efficacy of the two most cost effective insecticides for use against Heliothis has been maintained at an acceptable
level. Without these two insecticides, growing costs would escalate dramatically, probably so much so, that cotton could only be grown profitably in the !:!..:. armigera prone eastern areas, during periods of high cotton prices.
iii) The removal of the delay period in resistance monitoring, has allowed the forec.asting of potential problem periods, giving the agrochemical companies time to respond with supplies
of
alternative insecticides.
iv) The established pattern of resistance development in $tage 2 allows growers/consultants to make judicious insecticide choices in the critical Stage 2 period. Given pest pressure and a reasonable estimate of the resistance level, the only unknown t'actor left to determine is the percentage of
!:!..:. armigera.
DIFFICULTIES
The inability to quickly determine the percentage of !:!..:. armigera in the field.
FUTURE RESEARCH
i) The long term viability of the Strategy must be assessed by looking at the survival of the two main pyrethroid resistant genes in the unsprayed refugia. If these genes are not at a selective disadvantage in unsprayed crops, then they will gradually oo.ntaminate the refugia to such an extent, that dilution by immigrating susceptibles is no longer possible.
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ii) The relative importance of the two major resistance genes in field populations should be determined to assess the possible impact of 'introducing piperonyl butoxide as a synergist to counter metabolic pyrethroid resistance due to mixed function oxidase enzymes.
iii) The pyrethroid resistance gene imparting nerve insensitivity resistance, should be isolated to determine whether it reacts similarly to the mixed function oxidase metabolic resistance gene, particularly on newly hatched larvae.
iv) Pyrethroid and endosulfan resistance monitoring in .!:!.:.. punctigera should be incorporated in the current monitoring programme.
APPLICATION OF RESULTS TO INDUSTRY
i) The voluntary Insecticide Resistance Management Strategy has been adopted by the whole industry since its introduction in 1983/84, with all but total compliance. Regular industry meetings are held, particularly each winter, to refine the
guidelines of the Strategy. These meetings involve co-ordination and co-operation of every section of the cotton and grain growing industries and the agrochemical companies. The recommendations arising from these meetings are strongly dependent on the
accurate, reliable information on resistance levels, made available by this research.
ii) Cultivation of cotton residues is increasing in order to control the highly resistant overwintering population. Overwintering pupal sampling is being introduced.
iii) December flowering crops (eg, maize/sunflowers) are being avoided in predominately cotton areas due to their role as nursery crops for resistant .!:!.:.. armigera.
iv) Chemical choice in the critical Stage 2 period is now being made with regard to current resistance level, pest pressure, previous
insecticide use and neighbouring crops.
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LIST OF PUBLICATIONS
FORRESTER, N.W. (1983). Pyrethroid Resistance. The Australian Cotton Grower.
Vol 4 ( 3) : 4.
FORRESTER, N.W. (1983). Growers question on the Pyrethroid Resistance Strategy. The Australian Cotton Grower. Vol 4 (4) : 41
FORRESTER, N.W. (1984). Pyrethroid Resistance Strategy. The Australian Cotton Grower. Vol
s
(4) : 45CAHILL, M EASTON, C., FORRESTER, N.W. and GOODYER. G. (1984). Larval identification of Heliothis armiger and Heliothis punctiger. 1984 Australian Cotton Growers Research Conference, Toowoomba, Qld.
FORRESTER, N.W. and CAHILL, M. (1984). Managing pyrethroid resistant Heliothis armiger (Hubner). 15th Annual General Meeting of the Australian Entomological Society, Mildura, Vic.
CAHILL, M., EASTON·, C., FORRESTER, N.W. and GOODYER, G. (1984). Larval identification of Heliothis armiger (Huber) and Heliothis punctiger {Wallengren). 15th Annual General Meeting of the Australian
Entomological Society, Mildura, Vic.
FORRESTER. N.W. and CAHILL, M. (1984). Field evaluation of an insecticide management strategy for pyrethroid resistant Heliothis armiger (Hubner)
in Australia. XVII International Congress of Entomology, Hamburg, Germany.
FORRESTER, N.W. (i984) . Insecticide management strategy for pyrethroid resistant Heliothis armiger {Hubner). Fourth Australian Applied Entomological Research Conference, Adelaide, S.A.
FORRESTER, N.W. an~ CAHILL, M. (1984). Field evaluation of an insecticide management strategy for the control of pyrethroid resistant Heliothis armiger. 1984 Australian Cotton Growers Research Conference, Toowoomba.
Qld.
FORRESTER, N.W. (1985). Pyrethroid insecticide resistance : Heliothis Control Strategy for 1985/86. NSW Department of Agriculture Agfact AE:43 Agdex 622.
FORRESTER, N.W. (1985). Pyrethroid Insecticide Resistance - Control Strategy for Heliothis species in 1985/86. NSW Department of Agriculture Cotton Pesticides Guide. 1984-1985. Agdex 151/680.
FORRESTER, N.W. (1985). Pyrethroid Resistance Strategy - Retrospect and Prospect. The Australian Cotton Grower 6 (3) : 5-7.
FORRESTER, N.W. (1985). Insecticide use on cotton in the Namoi and Gwydir.
The Australian Cotton Grower 6 (4) : 6-9.
FORRESTER, N.W. (1985). Pyrethroid Resistance Monitoring at Emerald. The Australian Cotton Grower 6 (4) : 71.
FORRESTER, N.W., CAHILL, M. and TWINE, P.H. (1986), Insecticide resistance with special reference to a management strategy in Australia. 44th Plenary Meeting of the International Cotton Advisory Committee. Sydney.
Australia. Crop Protection. Supplement to Document 8.
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~age 6FORRESTER, N.W. and CAHILL. M. (1986). Management of insecticide resistance
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in Heliothis armigera - a critical assessment of results to date. Joint CSIRO - DSIR Workshop on the Management of Insecticide Resistance, Canberra; A.C.T.
FORRESTER, N.W. and CAHILL, M. (1986). Management of insecticide resistance in Heliothis armigera in Australia. British Society of Chemical Industry Symposium on the Fundamental and Practical Approaches to Combating
Resistance, Southampton. U.K.
FORRESTER, N.W. and CAHILL. M. (1986). Insecticide management strategy for control of resistant Heliothis armigera in Australia. Ive Congres
surla Protection de la Sante Humaine et des Cultures en Milieu Tropical, Marseilles. France.
FORRESTER, N.W. (1986). Chemical use and resistance - the threat and the costs. 1986 Australian Cotton Conference, Surfers Paradise, Qld.
FORRESTER, N.W. (1986). Monitoring the Strategy. The Australian Cotton Grower
7 ( 1) : 27.
FORRESTER, N.W. (1986). Insecticide Use on Cotton in the Namoi and Lower Gwydir. The Australian Cotton Grower 7 (4) : 5-7.
FORRESTER, N.W. and TWINE, P.H. (1986). Pyrethroid Strategy for 1986-87. The Australian Cotton Grower 7 (4) : 26.
FORRESTER, N.W., ALLSOPP, P.G. and KEMPSON, L. (1987). Insecticide use at Emerald 1985-86. The Australian Cotton Grower. 8 (1) : 44-48.
FORRESTER, N.W. and TWINE, P.H. (1987). Field Crop Insecticide Strategy for 1987-88. The Australian Cotton Grower 8 (3) : 30.
FORRESTER, N.W. and KEMPSON, L. (1987). Insecticide use at Emerald in 1986-87. The Australian Cotton Grower 8 (3) : 52-55.
FORRESTER, N.W. (1987). Alternate crops and pyrethroid resistance. The Australian Cotton Grower 8 (4) : 42.
FITT, G.D. and FORRESTER., N.W. (1987). Overwintering of heliothis : the importance of stubble cultivation. The Australian Cotton Grower 8 (4) 7-8.
FORRESTER, N.W. and CAHILL, M. (1987). Management of insecticide resistance in Heliothis arrnigera (Hubner) in Australia. in Combating Resistance to Xenobiotics. Biological and Chemical Approaches. eds. H.G. Ford, D.W.
Holloman, B.P.S. Khambay and R.M. Sawicki, Ellis Horwood, Chichester.
320 pp.
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